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開催日 2016/7/22
時間 11:00 - 11:50
会場 Exhibition Hall B
  • P3-087   Time: -
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サル初期視覚野第2層における方位マップと眼優位性マップの関係性: 2光子 カルシウムイメージングによる解析
Spatial relation between ocular dominance map and orientation map in layer II of macaque V1 at cellular level resolution.

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  • 竹内 F 遼介 / Ryosuke F Takeuchi:1 池添 貢司 / Koji Ikezoe:1,2,3 稲垣 未来男 / Mikio Inagaki:1,2 箔本 一仁 / Kazuhito Hakumoto:1 藤田 一郎 / Ichiro Fujita:1,2 
  • 1:大阪大院生命機能 / Grad Sch of Frontier Biosci, Osaka Univ 2:大阪大および情報通信研究機構・脳情報通信融合研究センター / CiNet, Osaka Univ & Natl Inst Commun Tech, Suita, Japan 3:山梨大院・総合研究部 生理学2 / Grad Faculty of Interdisciplinary Res, Univ of Yamanashi, Chuo, Japan 

Neurons in the primary visual cortex (V1) of monkeys are orderly arranged across the cortex according to their preferences to stimulus orientation and the eye of inputs (ocular dominance: OD). Intrinsic-signal optical imaging studies have shown that the orientation map and OD map are overlaid, and intersect orthogonally in linear zones where orientation preferences change along one axis. However, because the intrinsic-signal optical imaging techniques can measure only averaged activities of neurons in a local region, it remains unclear whether OD preference of neurons gradually changes across the cortex, and whether the orthogonal intersection of the two maps occurs at the single-cell level. Here, we examined spatial relation between the two maps at single-neuron resolution using two-photon calcium imaging techniques. We measured responses of neurons to drifting grating (10 different directions, 2 cycles/s, 1 cycle/°) in an immobilized monkey (Macaca fuscata) under opiate analgesia. Imaged regions spanned 300 μm x 300 μm and all of the imaged neurons were located in layer II. We loaded neurons with a calcium-sensitive dye (Cal-520 AM), and quantified their responses by calculating percentage changes in fluorescence intensity between the stimulus periods and blank periods. Seventy six out of 83 neurons showed a significant selectivity to drifting direction of gratings (Kruskal-Wallis test, P < 0.05). For each neuron, we quantified preferences for orientation and OD. For our analysis, we selected 46 neurons whose inter-ocular difference of preferred orientations was < 20°. OD-index (0 ~ 1 with 0.5 balanced inputs) differed across neurons. The difference between a pair of neurons positively correlated with their distance along the cortical surface (r = 0.22, P << 0.001, Pearson's correlation coefficient; P <<0.001, Permutation-test); nearby neurons tended to have a similar OD-index. The difference of their preferred orientation also became larger with inter-neuron distance (r = 0.19, P << 0.001 Pearson's correlation coefficient; P = 0.012, Permutation-test). The intersection angle of the two maps was close to orthogonal (84.8°: angle formed by the axes of maximum changes of preferred orientation and OD). Our analyses demonstrated that gradual OD and orientation maps exist simultaneously at the same area in layer II of macaque V1, and they intersect with each other at right angle as has been suggested by intrinsic optical imaging.

 

研究助成:Research funds : 25830012, 15K18357, 14J01649 and CiNet

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